The present disclosure relates generally to methods for estimating the in situ density of light hydrocarbons. More specifically, in certain embodiments, the present disclosure relates to methods for estimating in situ density of light hydrocarbons in shale source rock vein and matrix minerals using Raman spectroscopy and associated methods.
One of the objectives of an exploration and appraisal campaign in unconventional shale gas and liquid rich shale plays is to “sweet spot” the acreage in terms of potential estimated ultimate recovery (EUR). Sweet spotting is a term used to refer to the identification of the top quartile wells in a given production zone. This is often difficult to do in the absence of reliable production data. Estimating EUR in shale gas formations is especially challenging since EUR is a dynamic production metric while all other rock properties being measured are static in-situ properties. The relationship between these different states is not intuitive and presently poorly understood. In order to successfully sweet spot an unconventional shale source rock play, an estimate of the mass of light hydrocarbon per volume of source rock (i.e. the in situ density of light hydrocarbon) is required.
It is desirable to develop a method of determining in situ density and pressure of light hydrocarbons in a gas-bearing shale source rock in order to develop accurate EUR maps and identify sweet spots in the shale source rock formations.